The present invention relates to a novel prosthetic substitute member for living body and a method for the surgical treatment by use of the prosthetic substitute member. In particular, the present invention relates to a novel artificial bone member exhibiting unexpectedly high affinity to the living tissue when embedded in a living body as a substitution for a damaged or broken bone as well as to a method for the surgical treatment using such an artifical bone member.
In recent years, artificial bone members and artificial bone setting materials are widely used in the fields of the orthopedic surgery for the cure of fractured bones, orthopedic treatment or prosthetic substitution of bones and the like. These artificial materials for living body use are required to have sufficiently high mechanical strengths to withstand the large load which the bone undergoes, to have excellent affinity to the living body tissues so as that the artificial bone member embedded in the living body becomes a part of the living body as early as possible after the surgical treatment, to be physiologically inert to the living body, for example, without leaching of poisonous ions into the tissue in which the member is embedded and to have excellent workability to be shaped into any complicated form of the human bones.
In the prior art, most of the artificial bone members are made of a metallic material such as stainless steels, cobalt-based Vitallium alloys containing chromium and molybdenum, titanium and its alloys, tantalum and the like. These metallic materials are satisfactory to some extent in respect of the mechanical strengths and workability to be in compliance with diversified application. These materials are, however, not always satisfactory in the adaptability to the living body. For example, metals generally have no sufficiently high affinity to the living tissues so that the postoperative care is necessarily prolonged. In addition, metallic materials are not without physiologically adverse effects to the living tissues. For example, the surface of the metallic artificial bone member is eroded or abraded to form minute particles which may be deleterious to the tissues in the vicinity of the implanted artificial bone member. Furthermore, the metallic elements in the artificial member may be ionized producing ions which act adversely or poisonously in the living tissues.
As an alternative to the metallic materials, there have been recently proposed several kinds of oxide or ceramic materials not only for prosthetic bone substitutes but also for artificial teeth. Examples of them are, for example, sapphire which is a single crystal aluminum oxide, polycrystalline sintered or porous alumina, yttrium oxide and the like. These ceramic materials are preferable in respects of the affinity and physiological inertness to the living body tissues in comparison with the above mentioned metallic materials. The ceramic materials are, however, in general inferior in the mechanical strengths or, in particular, shock absorption and tenacity due to the inherent brittleness and in the workability so as that fine working of complicated members such as screw thread formation is used an unsurmountable limitation. Single crystalline materials such as sapphire of course have a higher mechanical strength than polycrystalline sintered ceramic materials but are difficult to be fabricated into members of complicated forms if not to mention the outstanding expensiveness.